In this paper, we present a novel robotic system for heliography, which literally refers to painting with the sun. In the context of artistic creation, heliography involves the precise manipulation of a magnifying glass to burn artwork on wooden panels by concentrating solar energy. Since this painting procedure exposes the human operator to prolonged periods of intensive sunlight, it can potentially cause sunburns to the skin or damage the eyes. To avoid these issues, in this paper we propose to automate the heliography process with a robot in lieu of a human operator. The proposed thermal servoing capabilities have the potential to robotize various solar power generation technologies such as Concentrated Solar Power (CSP) and Concentrated Photovoltaics (CPV). To perform this task, our robotic system is equipped with a magnifying glass attached to the end-effector, and is instrumented with vision and thermal sensors; The proposed sensorbased controls enable to automatically: 1) Track the orientation of the sun in real-time to maximize the concentrated solar energy; 2) Direct the solar rays towards the point of interest; 3) Control the heat power intensity at the target point to achieve the required steady state temperature. The performance of our system is evaluated by conducting autonomous heliography experiments with various patterns.